Equipment for the laser-cutting of metal sheets

ABSTRACT

Equipment for the laser cutting of metal sheets is to hold the metal sheets in a vertical plans by means of a laser-focusing head ( 10 ) which is movable in a vertical plans relative to the metal sheet ( 12 ). The equipment includes an abutment member ( 18 ) carried by the focusing head ( 10 ) and intended to bear against that face ( 20 ) of the sheet ( 12 ) facing the focusing head ( 10 ).

TECHNICAL FIELD

The present invention relates to equipment for the laser-cutting ofmetal sheets, comprising;

means for supporting a metal sheet to be cut in a substantially verticalplane, and

a laser-focusing head movable relative to the metal sheet in a verticalplans.

BACKGROUND ART

Integrated equipment for the laser-cutting and bending of pieces ofsheet metal is known from Italian Patent Application No. TO95A00569, bythe same Applicants, in which the sheets to be cut are held in avertical plane.

Several problems arise in the laser-cutting of metal sheets held in avertical position which do not generally occur in more conventionalcases in which the metal sheet to be cut rests on a horizontal surface.A first problem arises when cutting is effected along a closed path soas to produce a through-hole, of any profile, in the metal sheet. Inthis case a waste piece is produced having a shape corresponding to thatof the aperture to be formed. At the end of the cutting process, thewaste piece could fall towards the laser-focusing head. There is thus adanger of the laser-focusing head being hit by the waste piece, causingjamming or damage to the focusing head. A second problem results fromthe fact that the metal sheet is generally suspended from its upperhorizontal edge and, during working, may oscillate or vibrate so thatthe distance between the leaser-focusing head and the surface of thesheet metal being cat varies. The focusing head usually has a capacitivedistance sensor which adjusts the distance of the head from the surfaceto be cut. In fact it is important for this distance to be keptconstantly at a predetermined value to ensure correct focusing of thelaser beam. However, when the sheet metal vibrates or oscillatesrapidly, the head cannot follow the movement of the surface because ofthe inertia of the distance sensor and the kinematic(cinematic) chainwhich controls the movement of the focusing head in a directionperpendicular to the metal sheet.

DISCLOSURE OF INVENTION

The present invention has been achieved with such a point in mind.Therefore, the object of the present invention is to provide equipmentfor the laser-cutting of sheets in a vertical plane which overcomes thesaid problems.

According to the present invention, this object is achieved by virtue ofthe fact that the equipment includes an abutment member carried by thefocusing head and intended to bear against that face of the sheet to becut which faces the focusing head.

The abutment member prevents the waste pieces from falling towards thefocusing head and knocking or jamming of the focusing head against thepieces. Moreover the abutment member makes the system for supporting thesheet metal more rigid and considerably reduces the possibility of thesheet vibrating or oscillating, particularly in the cutting zone.

BRIEF DESCRIPTION OF DRAWINGS

Further characteristics and advantages of the present invention willbecome apparent during the detailed description which follows, givenpurely by way of non-limitative example, with reference to the appendeddrawings, in which:

FIG. 1 is a schematic view of a first embodiment of equipment accordingto the present invention;

FIG. 2 illustrates the equipment of FIG. 1 schematically during theformation of a cut in correspondence with a member which grips the metalsheet;

FIG. 3 is an axial section illustrating a second embodiment of anabutment member according to the present invention; and

FIG. 4 illustrates schematically the equipment of FIG. 3 in an initialphase of cutting.

BEST MODE FOR CARRYING OUT THE INVENTION

There will be detailed below the preferred embodiments of the presentinvention with reference to the accompanying drawings. Like members aredesignated by like reference characters.

With reference initially to FIGS. 1 and 2, a laser-focusing head isgenerally indicated 10 and forms part of automatic laser-cuttingequipment, for example of the type described in detail in Italian PatentApplication No. TO95A000569. The laser-focusing head 10 is carried by adrive structure of known type constituted, for example, by a cartesian[X, Y] robot which enables the head 10 to be moved in a vertical workingplane.

A metal sheet intended to be cut by means of the head 10 is indicated12. The sheet 12 is held suspended in a vertical plane parallel to theplane of movement of the head 10 by means of gripper membersconstituted, for example, by jaws such as those indicated 14 in FIG. 2.The jaws 14 grasp the metal sheet 12 by a portion adjacent itshorizontal upper edge 16.

According to the present invention, the laser-focusing head 10 carriesan abutment member 18 which, in use, is intended to bear against thatface 20 of the metal sheet 12 facing the focusing head 10. In theembodiment illustrated in FIGS. 1 and 2, the abutment member 18 isgenerally in the form of a brush and comprises a disc-like annularmember 22 carrying a plurality of filiform elements 24 grouped in tuftsand defining an abutment surface intended to contact the face 20 of thesheet 12. The filiform elements 24 forming the bristles of the brushmay, for example, be of bronze, plastics or other material.

In a preferred embodiment of the present invention, the abutment member18 is connected to the laser-focusing head 10 so that it can oscillateabout a generic axis parallel to the face 20. This connection ispreferably formed by resilient members 26, each of which has a first endfixed to the body 22 and a second end fixed to the focusing head 10. Theability of the abutment member 18 to float relative to the focusing head10 is useful particularly when it is necessary to form cuts close to thejaws 14 which hold the metal sheet 12. As illustrated in FIG. 2, theabutment member 18 may surmount the jaw 14, disposing itself in aninclined position. Thus the head 10 may operate even in the immediatevicinity of the jaws 14.

In rest conditions, the distance between the front face 29 of thefocusing head 10 and the abutment face of the abutment member 18 isequal to, or slightly greater than, the distance (indicated D in FIG. 1)that it is necessary to maintain between the front face 29 and the face20 of the piece 12 for correct focusing of the laser beam. Hence, inuse, the abutment face of the abutment member 18 is lightly loaded intosliding contact with the face 20. The member 18 thus provides a stableabutment for the sheet 12 and considerably reduces the possibility of itvibrating or oscillating. The reduction in the oscillating or vibratingmovement of the sheet 12 is particularly marked in the abutment zonesurrounding the cutting zone.

Moreover the abutment member 18 prevents waste pieces and swarf formedwhen holes or apertures are cut from falling towards the focusing head10. In fact, the presence of an abutment surface facing the surface 20of the metal sheet 12 ensures that the swarf and waste pieces alwaysfall away from the focusing head 10, avoiding any risk of damage to, orjamming of, the head 10.

FIGS. 3 and 4 illustrate an improved embodiment of the abutment memberof the present invention. The brush-like abutment member described abovehas the disadvantage that, during the initial piercing the metal sheet12, the gas let supplied by the laser-focusing head 10 is projectedrearwardly, entraining with it the molten material which tends tocollect on the filiform elements 24 and in the space formed between thenozzle of the laser head 10 and the bristles 24.

The object of the version of the abutment member illustrated in FIGS. 3and 4 is to overcome this problem.

With reference to FIGS. 3 and 4, the abutment member 18 comprises twoshaped discs 25 and 30, preferably made from self-lubricating plasticsmaterial (typically TEFLON Registered Trade Mark). The two discs 28, 30are kept separated from each other by spacer elements 32 so that theydefine an annular channel 38 between the facing surfaces 34, 36 of thetwo discs 28, 30. As illustrated in FIG. 4, the shape of the channel 38means that the flow of gas and molten material which forms during theinitial phase of the piercing of the metal sheet 12 is deflected alongthe channel 38 in a radially-outward movement as shown schematically bythe arrows 40. The walls 34, 36 of the channel 38 are smooth andfacilitate the outward sliding flow of the dust and molten materialentrained by the gas flow. Moreover, it has been found experimentallythat the molten material transported by the gas flow has very littleaffinity for the self-lubricating plastics material constituting the twodiscs 28, 30 and slides over the walls 34, 36 without forming depositsand without damaging the discs 28, 30. In the version illustrated inFIGS. 3 and 4, the abutment member 18 is again connected to thelaser-focusing head 10 in a floating manner. This connection is achievedby means of a series of leaf springs 42 spaced circumferentially aroundthe outer edge of the abutment member 18. Respective first ends of theleaf springs 42 are fixed to the spacers 32 which connect the discs 28,30 together. Respective second ends of the leaf springs 42 are connectedto support elements 44 fixed to the laser-focusing head 10, for exampleby screws 46. Like the embodiment described above, the disc 28 presentsa flat abutment surface 48 which, in rest conditions, is spaced from thefront surface 29 of the laser-focusing head by a distance equal to, orslightly greater than, the distance D between the front surface 29 ofthe laser head 10 and the face 20 of the sheet 12 in operativeconditions.

This invention is not limited for the embodiments described above. Forexample, the jaws is arranged for supporting a metal sheet 12 to be cutin a horizontal lane instead of the vertical plane, and the laserfocusing head 10 can be designed to move relative to the metal sheet 12in a horizontal plane instead of the vertical plane.

While preferred embodiments of the present invention have been describedusing specific terms, such description is for illustrative purposes, andit is to be understood that changes and variations may be made withoutdeparting from the spirit or scope of the following claims.

INDUSTRIAL APPLICABILITY

As stated hereinbefore, the equipment for the laser cutting of metalsheets according to the invention is applicable for use in laser cuttingmachines, especially for a laser cutting machine which comprises jawmember for supporting a metal sheet to be cut in a horizontal orvertical plane and a laser focusing head movable relative to the metalsheet in a horizontal or vertical plane.

What is claimed is:
 1. Equipment for the laser cutting of metal sheets,comprising: means for supporting a metal sheet to be cut in a plane, alaser focusing head movable relative to the metal sheet in a plane; andan abutment member carried by the focusing head and intended to bearagainst that face of the sheet facing the focusing head; wherein theabutment member comprises two shaped discs spaced from each other andhaving respective mutually facing surfaces which define a channel forthe evacuation of a return gas flow.
 2. Equipment according to claim 1,wherein at least one of the shaped discs is made from self-lubricatingplastics material.
 3. Equipment for the laser cutting of metal sheets,comprising: means for supporting a metal sheet to be cut in asubstantially vertical plane; a laser focusing head movable relative tothe metal sheet in a vertical plane; and an abutment member carried bythe focusing head and intended to bear against that face of the sheetfacing the focusing head; wherein the abutment member comprises anannular body having a plurality of filiform elements arranged in a brushconfiguration.
 4. Equipment for the laser cutting of metal sheets,comprising: means for supporting a metal sheet to be cut in asubstantially vertical plane; a laser focusing head movable relative tothe metal sheet in a vertical plane; and an abutment member carried bythe focusing head and intended to bear against that face of the sheetfacing the focusing head; wherein the abutment member comprises twoshaped discs spaced from each other and having respective mutuallyfacing surfaces which define a channel for the evacuation of a returngas flow.
 5. Equipment for the laser cutting of metal sheets,comprising: means for supporting a metal sheet to be cut in asubstantially vertical plane; a laser focusing head movable relative tothe metal sheet in a vertical plane; and an abutment member carried bythe focusing head and intended to bear against that face of the sheetfacing the focusing head; wherein the abutment member is generallyannular and surrounds an end portion of the focusing head; and whereinthe abutment member comprises two shaped discs spaced from each otherand having respective mutually facing surfaces which define a channelfor the evacuation of a return gas flow.
 6. Equipment for the lasercutting of metal sheets, comprising: means for supporting a metal sheetto be cut in a substantially vertical plane; a laser focusing headmovable relative to the metal sheet in a vertical plane; and an abutmentmember carried by the focusing head and intended to bear against thatface of the sheet facing the focusing head; wherein the abutment memberpresents a front abutment surface which, in rest conditions, is spacedfrom a facing surface of the focusing head by a distance equal to, orslightly greater than, the distance which, in operative conditions, liesbetween the front face of the focusing head and the face of the sheet tobe cut; and wherein the abutment member comprises two shaped discsspaced from each other and having respective mutually facing surfaceswhich define a channel for the evacuation of a return gas flow. 7.Equipment for the laser cutting of metal sheets, comprising: means forsupporting a metal sheet to be cut in a substantially vertical plane; alaser focusing head movable relative to the metal sheet in a verticalplane; and an abutment member carried by the focusing head and intendedto bear against that face of the sheet facing the focusing head; whereinthe abutment member is connected to the focusing head so as to be ableto pivot about a generic axis parallel to the plane of movement of thehead; and wherein the abutment member comprises two shaped discs spacedfrom each other and having respective mutually facing surfaces whichdefine a channel for the evacuation of a return gas flow.
 8. Equipmentfor the laser cutting of metal sheets, comprising: means for supportinga metal sheet to be cut in a substantially vertical plane; a laserfocusing head movable relative to the metal sheet in a vertical plane;and an abutment member carried by the focusing head and intended to bearagainst that face of the sheet facing the focusing head; wherein theabutment member is connected to the focusing head so as to be able topivot about a generic axis parallel to the plane of movement of thehead; wherein the connection between the abutment member and thefocusing head is formed by resilient means; and wherein the abutmentmember comprises two shaped discs spaced from each other and havingrespective mutually facing surfaces which define a channel for theevacuation of a return gas flow.
 9. Equipment for the laser cutting ofmetal sheets, comprising: means for supporting a metal sheet to be cutin a substantially vertical plane; a laser focusing head movablerelative to the metal sheet in a vertical plane; and an abutment membercarried by the focusing head and intended to bear against that face ofthe sheet facing the focusing head; wherein the abutment member isgenerally annular and surrounds an end portion of the focusing head; andwherein the abutment member comprises an annular body having a pluralityof filiform elements arranged in a brush configuration.
 10. Equipmentfor the laser cutting of metal sheets, comprising: means for supportinga metal sheet to be cut in a substantially vertical plane; a laserfocusing head movable relative to the metal sheet in a vertical plane;and an abutment member carried by the focusing head and intended to bearagainst that face of the sheet facing the focusing head; wherein theabutment member presents a front abutment surface which, in restconditions, is spaced from a facing surface of the focusing head by adistance equal to, or slightly greater than, the distance which, inoperative conditions, lies between the front face of the focusing headand the face of the sheet to be cut; and wherein the abutment membercomprises an annular body having a plurality of filiform elementsarranged in a brush configuration.
 11. Equipment for the laser cuttingof metal sheets, comprising: means for supporting a metal sheet to becut in a substantially vertical plane; a laser focusing head movablerelative to the metal sheet in a vertical plane; and an abutment membercarried by the focusing head and intended to bear against that face ofthe sheet facing the focusing head; wherein the abutment member isconnected to the focusing head so as to be able to pivot about a genericaxis parallel to the plane of movement of the head; and wherein theabutment member comprises an annular body having a plurality of filiformelements arranged in a brush configuration.
 12. Equipment for the lasercutting of metal sheets, comprising: means for supporting a metal sheetto be cut in a substantially vertical plane; a laser focusing headmovable relative to the metal sheet in a vertical plane; and an abutmentmember carried by the focusing head and intended to bear against thatface of the sheet facing the focusing head; wherein the abutment memberis connected to the focusing head so as to be able to pivot about ageneric axis parallel to the plane of movement of the head; wherein theconnection between the abutment member and the focusing head is formedby resilient means; and wherein the abutment member comprises an annularbody having a plurality of filiform elements arranged in a brushconfiguration.